From 733214144a7a910001c1c82683db780853bac9b1 Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Wed, 22 Jan 2014 00:33:18 +0000
Subject: Document dynamic attributes

Signed-off-by: Shea Levy <shea@shealevy.com>
---
 doc/manual/release-notes.xml           |  6 ++++++
 doc/manual/writing-nix-expressions.xml | 21 +++++++++++++++++----
 2 files changed, 23 insertions(+), 4 deletions(-)

(limited to 'doc')

diff --git a/doc/manual/release-notes.xml b/doc/manual/release-notes.xml
index 37bb730f4..56f7bd654 100644
--- a/doc/manual/release-notes.xml
+++ b/doc/manual/release-notes.xml
@@ -21,6 +21,12 @@
   <listitem><para><command>nix-setuid-helper</command> is
   gone.</para></listitem>
 
+  <listitem><para>Now antiquotation is allowed inside of quoted
+  attribute names (e.g. <literal>set."${foo}"</literal>). In the
+  case where the attribute name is just a single antiquotation,
+  the quotes can be dropped (e.g. the above example can be written
+  <literal>set.${foo}</literal>).</para></listitem>
+
 </itemizedlist>
 
 </section>
diff --git a/doc/manual/writing-nix-expressions.xml b/doc/manual/writing-nix-expressions.xml
index c5b355ea0..71cd84b07 100644
--- a/doc/manual/writing-nix-expressions.xml
+++ b/doc/manual/writing-nix-expressions.xml
@@ -851,13 +851,26 @@ default value in an attribute selection using the
 will evaluate to <literal>"Xyzzy"</literal> because there is no
 <varname>c</varname> attribute in the set.</para>
 
-<para>You can use arbitrary string constants as attribute names by
-enclosing them in quotes:
+<para>You can use arbitrary double-quoted strings as attribute
+names:
 
 <programlisting>
-{ "foo bar" = 123; "nix-1.0" = 456; }."foo bar" </programlisting>
+{ "foo ${bar}" = 123; "nix-1.0" = 456; }."foo ${bar}"
+</programlisting>
+
+This will evaluate to <literal>123</literal> (Assuming
+<literal>bar</literal> is antiquotable). In the case where an
+attribute name is just a single antiquotation, the quotes can be
+dropped:
+
+<programlisting>
+{ foo = 123; }.${bar} or 456 </programlisting>
+
+This will evaluate to <literal>123</literal> if
+<literal>bar</literal> evaluates to <literal>"foo"</literal> when
+coerced to a string and <literal>456</literal> otherwise (again
+assuming <literal>bar</literal> is antiquotable).</para>
 
-This will evaluate to <literal>123</literal>.</para>
 
 </simplesect>
 
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